Disk rotating motor with bracket defining cylindrical and folded portions, and disk drive device provided with the same

ABSTRACT

A disk rotating motor is provided with: a stator including a stator core and a bracket for fixing the stator core; a rotor that can be rotated with respect to the stator and includes a shaft; and a bearing that rotatably supports the rotary shaft on the outer diameter side of the rotary shaft. The bracket includes a cylindrical portion extending along the shaft and a folded portion formed by folding the upper end of the cylindrical portion onto the outer diameter side. The bearing is fixed to the inner circumferential surface of the cylindrical portion whereas the stator core is fixed to the outer peripheral surface of the folded portion.

This application is based on Japanese Patent Application No. 2011-229486filed with the Japan Patent Office on Oct. 19, 2011, the entire contentof which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a disk rotating motor and a disk drivedevice provided with the same and, more particularly, to a disk rotatingmotor that can be fabricated in a simple method and a disk drive deviceprovided with the same.

2. Description of the Related Art

When information is written in or read from a recording medium havinginformation recorded therein such as an optical disk or amagneto-optical disk, a disk drive device is used to rotate a disk. Thedisk drive device includes a disk rotating motor for rotating the disk.The techniques relevant to the disk rotating motor in the prior art aredisclosed in, for example, Documents 1, and 2.

Document 1, discloses a brushless motor including a burring unitconstituting a bearing housing and a fixing base unit for fixing themotor, the units being formed integrally with each other.

Document 2, discloses a spindle motor including a bracket having anannular recess and a cylindrical opening, the bracket being integrallymolded by pressing. The annular recess is formed in an axial direction,and contains a stator and a rotor magnet therein. A shaft is fitted tothe inner circumference of the cylindrical opening.

-   Document 1:, Japanese Patent Laying-Open No. 2002-262540-   Document 2:, Japanese Patent Laying-Open No. 2001-314058

Cost reduction has been strongly required for the disk rotating motor inrecent years. In order to reduce the cost of the disk rotating motor,the disk rotating motor needs be fabricated in a simple method. Forexample, the number of component parts for the disk rotating motor isreduced; or not a relatively complicated (i.e., expensive) processingmethod such as cutting but a relatively simple (i.e., inexpensive)method such as pressing needs be used to process component partsconstituting the disk rotating motor. Moreover, not a complicatedtightening method but a relatively easy (i.e., inexpensive) tighteningmethod typified by press-fitting need be adopted with high assemblingprecision in assembling the component parts. The prior art has beensusceptible to improvement from the viewpoint of simplification of thefabricating method.

SUMMARY OF THE INVENTION

The present invention has been accomplished to solve the above-describedproblems to be solved. Therefore, an object of the present invention isto provide a disk rotating motor that can be fabricated by a simplemethod and a disk drive device provided with the same.

A disk rotating motor according to one aspect of the present inventionis provided with: a stator including a stator core and a bracket forfixing the stator core; a rotor that can be rotated with respect to thestator and includes a rotary shaft; and a bearing that rotatablysupports the rotary shaft on the outer diameter side of the rotaryshaft; the bracket including a cylindrical portion extending along therotary shaft and a folded portion formed by folding the end of thecylindrical portion onto the outer diameter side, and the bearing beingfixed to the inner circumferential surface of the cylindrical portionwhereas the stator core being fixed to the outer peripheral surface ofthe folded portion.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the configuration of a disk drivedevice in an embodiment according to the present invention.

FIG. 2 is a cross-sectional view schematically showing the configurationof a disk rotating motor in the embodiment according to the presentinvention.

FIG. 3 is a cross-sectional perspective view schematically showing theconfiguration of the disk rotating motor in the embodiment according tothe present invention.

FIG. 4 is a perspective view showing the configuration of a bracket 23.

FIGS. 5 and 6 are schematic views illustrating a fabricating method forthe disk rotating motor in a first embodiment according to the presentinvention.

FIG. 7 is a cross-sectional view schematically showing the configurationof a disk rotating motor in a second embodiment according to the presentinvention.

FIG. 8 is a cross-sectional perspective view schematically showing theconfiguration of the disk rotating motor in the second embodimentaccording to the present invention.

FIG. 9 is a cross-sectional view schematically showing the configurationof a disk rotating motor in a third embodiment according to the presentinvention.

FIG. 10 is a cross-sectional perspective view schematically showing theconfiguration of the disk rotating motor in the third embodimentaccording to the present invention.

FIG. 11 is a cross-sectional view schematically showing theconfiguration of a disk rotating motor in a fourth embodiment accordingto the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments according to the present invention will bedescribed with reference to the attached drawings.

In the following description, “an outer diameter side” signifies anouter diameter side when the rotary shaft of a disk rotating motor isreferred to as the center whereas “an inner diameter side” signifies aninner diameter side when the rotary shaft of the disk rotating motor isreferred to as the center. Moreover, “an outer peripheral surface”signifies an outer peripheral surface when the rotary shaft of the diskrotating motor is referred to as the center whereas “an innercircumferential surface” signifies an inner circumferential surface whenthe rotary shaft of the disk rotating motor is referred to as thecenter.

[First Embodiment]

Referring to FIG. 1, a disk drive device in the present embodiment isprovided with a motor 100 serving as a disk rotating motor and acontroller 200 for controlling the drive state of motor 100 such asON/OFF or a rotational speed.

FIGS. 2 and 3 are views schematically showing the configuration of thedisk rotating motor in the embodiment according to the presentinvention, wherein FIGS. 2 and 3 are a cross-sectional view and across-sectional perspective view, respectively.

Referring to FIGS. 2 and 3, motor 100 includes mainly a rotor 10, astator 20, and a bearing 30. Rotor 10 can be rotated with respect tostator 20. Bearing 30 rotatably supports rotor 10 with respect to stator20.

Rotor 10 includes a rotor frame 11, a magnet 12, a shaft 13, and astopper washer 14. Rotor frame 11 is adapted to prevent a magnetic fieldfrom leaking from the inside of rotor frame 11, and is typified by amagnetic member. Rotor frame 11 includes a turn table 11 a, and a sidewall 11 b. Turn table 11 a, extends in, for example, a directionperpendicular to the extension direction of shaft 13 (laterally in FIG.2) (hereinafter often referred to as an axial direction). Turn table 11a, is formed into a circular shape, as viewed on a plane. A hole 60 isformed at the center of turn table 11 a, so as to allow shaft 13 to passtherethrough. Rotor frame 11 is fixed to shaft 13 at hole 60. Side wall11 b, extends toward a bracket 23 in stator 20 from an end on an outerdiameter side of turn table 11 a, (downward in FIG. 2). Side wall 11 b,is formed into a cylindrical shape.

Magnet 12 is fixed to the inner circumferential surface of side wall 11b. Magnet 12 is formed into an annular shape, and includes regionsmagnetized to an N pole and regions magnetized to an S pole alternatelyat constant intervals in a circumferential direction. Magnet 12 is fixedto rotor frame 11 in such a manner as to face stator 20.

Shaft 13 extends in a vertical direction in FIG. 2 in such a manner asto pass through the center of rotor frame 11 (i.e., the center in FIG.2). Rotor frame 11 can be rotated on shaft 13 together with shaft 13.Shaft 13 is rotatably supported by bearing 30 arranged around shaft 13on the outer diameter side.

Stopper washer 14 is fitted to a groove 13 a, formed at shaft 13 nearthe lower end of shaft 13 in FIG. 2. When shaft 13 is moved upward inFIG. 2, stopper washer 14 is brought into contact with bearing 30,thereby preventing shaft 13 from falling off upward in FIG. 2. Stopperwasher 14 is positionally restricted between bearing 30 and a thirdbottom 23 c.

Stator 20 includes a stator core 21 (i.e., a core), a stator coil 22,bracket 23, a bottom plate 24, and a thrust plate 25. Stator core 21 isfixed to bracket 23. Stator core 21 includes a plurality of teeth 21 a,radially extending from its inner diameter side toward its outerdiameter side. Stator coil 22 is wound around each of teeth 21 a.Bracket 23 is adapted to fix stator core 21. Bottom plate 24 is made of,for example, a magnetic material, and is fixed onto a rotor 10 side inbracket 23.

FIG. 4 is a perspective view showing the configuration of bracket 23.FIG. 4( a) viewed from rotor 10 whereas FIG. 4( b) is viewed oppositelyto rotor 10.

Referring to FIGS. 2 to 4, bracket 23 includes a first bottom 23 a,, asecond bottom 23 b,, third bottom 23 c,, a cylindrical portion 23 d,, afolded portion 23 e, (i.e., bracket folded portion), and an outer edge23 f. Cylindrical portion 23 d, extends in an axial direction. First tothird bottoms 23 a, to 23 c, are formed by bending the lower end ofcylindrical portion 23 d, in FIG. 2 toward the inner diameter side,thereby supporting the lower end of shaft 13 in FIG. 2. First bottom 23a, is located nearest the lower end of shaft 13 in FIG. 2 in bracket 23,and extends in a lateral direction in FIG. 2. Second bottom 23 b,extends in the axial direction between the outer-diameter end of firstbottom 23 a, and the inner-diameter end of third bottom 23 c. Thirdbottom 23 c, extends in the lateral direction in FIG. 2 between thelower end of cylindrical portion 23 d, and the upper end of secondbottom 23 b. Folded portion 23 e, is formed by folding the upper end ofcylindrical portion 23 d, in FIG. 2 toward the outer diameter side.Folded portion 23 e, extends downward of the boundary with cylindricalportion 23 d, in FIG. 2. Outer edge 23 f, extends from theouter-diameter end of folded portion 23 e, outward of the outer-diameterend of stator core 21. Cylindrical portion 23 d, defines a bearingcontainer. Folded portion 23 e, serves as a core fixing portion.

Bearing 30 is fixed at the inner circumferential surface of cylindricalportion 23 d. Bearing 30 is formed into a cylindrical shape, and extendsalong shaft 13. The outer peripheral surface of bearing 30 is broughtinto contact with the inner circumferential surface of cylindricalportion 23 d.

Stator core 21 is fixed at the outer peripheral surface of foldedportion 23 e. Stator core 21 has a bore 61 formed at the inner-diameterend thereof. The inner circumferential surface of bore 61 is broughtinto contact with the outer peripheral surface of folded portion 23 e.

Thrust plate 25 is formed into, for example, a circular shape, and has acontact surface in contact with the lower end of shaft 13 in FIG. 2.Thrust plate 25 receives a thrust load of shaft 13. First bottom 23 a,is brought into contact with thrust plate 25 on a side opposite to thecontact surface of thrust plate 25 with shaft 13. Second bottom 23 b,surrounds the outer periphery of thrust plate 25.

Motor 100 further includes a centering member 41 and a cushion rubber42. Turn table 11 a, has an inner-diameter end 11 c, bent upward in FIG.2. Centering member 41 is fixed at the outer peripheral surface ofinner-diameter end 11 c. A spring, not shown, is interposed betweencentering member 41 and inner-diameter end 11 c,, to thus bias centeringmember 41 towards the outer-diameter direction. Cushion rubber 42 isdisposed at the upper surface of turn table 11 a, in FIG. 2. When a disk80 is mounted on the disk drive device, disk 80 is mounted on cushionrubber 42 in such a manner that an opening 80 a, formed at the centerthereof is fitted to centering member 41. Centering member 41 pressesthe inner circumferential surface of opening 80 a, of disk 80 by theeffect of the spring, thereby fixing disk 80. Cushion rubber 42 isadapted to suppress the vertical vibration of disk 80 in FIG. 2.

Next, a description will be given of one example of a fabricating methodfor the disk rotating motor in the present embodiment with reference toFIGS. 5 and 6.

Referring to FIG. 5, first of all, one metallic plate, for example, isplastically machined by pressing or the like, thereby fabricatingbracket 23. Subsequently, as indicated by an arrow A1, folded portion 23e, is fitted into bore 61 of stator core 21, so that stator core 21 issecurely press-fitted to bracket 23.

Referring to FIG. 6, as indicated by an arrow A2, bearing 30 is thenfitted to cylindrical portion 23 d, of bracket 23, to be thus securelypress-fitted to bracket 23.

Returning to FIG. 2, a suction magnet 44 (FIG. 7) is disposed at apredetermined position, as required. Then, shaft 13 is inserted intobearing 30, so that rotor 10 is disposed in stator 20. Thereafter,centering member 41 and cushion rubber 42 are mounted on rotor frame 11,thus completing motor 100.

The present embodiment can provide the disk rotating motor that can befabricated in a simple method and a disk drive device provided with thesame.

In the present embodiment, bracket 23 including cylindrical portion 23d, for fixing bearing 30 and folded portion 23 e, for fixing the statorcore is fabricated by bending one plate, thus reducing the number ofcomponent parts and reducing the number of assembling processes. As aconsequence, it is possible to fabricate motor 100 in a simple method,so as to reduce the cost of the motor.

Moreover, first to third bottoms 23 a, to 23 c, supporting the lower endof shaft 13 in FIG. 2 are fabricated by bending one plate together withcylindrical portion 23 d, and folded portion 23 e,, thus reducing thenumber of component parts and reducing the number of assemblingprocesses. As a consequence, it is possible to fabricate motor 100 in asimple method, so as to reduce the cost of the motor.

Additionally, bracket 23 includes first bottom 23 a, in contact withthrust plate 25 and second bottom 23 b, that is formed by bending firstbottom 23 a, and surrounds the outer periphery of thrust plate 25, thusrestricting the position of thrust plate 25.

[Second Embodiment]

FIGS. 7 and 8 are views schematically showing the configuration of adisk rotating motor in a second embodiment according to the presentinvention, wherein FIG. 7 is a cross-sectional view whereas FIG. 8 is across-sectional perspective view.

Referring to FIGS. 7 and 8, the present embodiment is different from thefirst embodiment in that a motor 100 further includes a suction magnet44. Suction magnet 44 fulfills the function of magnetically sucking arotor 10 (herein a rotor frame 11) so as to stabilize the axial positionof rotor 10. Suction magnet 44 is fitted to the outer peripheral surfaceof a bearing 30 on the boundary (i.e., at a folding position) between acylindrical portion 23 d, and a folded portion 23 e. Suction magnet 44is fixed to the outer peripheral surface of bearing 30 in such a manneras to be brought into contact with the boundary between cylindricalportion 23 d, and folded portion 23 e.

Incidentally, the configuration of motor 100 except the above-describedmatter is identical to that of the motor in the first embodiment, andtherefore, its description is not repeated here.

In the present embodiment, the position of suction magnet 44 can berestricted on the boundary between cylindrical portion 23 d, and foldedportion 23 e. As a consequence, suction magnet 44 can suck rotor 10 byuniform suction force.

[Third Embodiment]

FIGS. 9 and 10 are views schematically showing the configuration of adisk rotating motor in a third embodiment according to the presentinvention, wherein FIG. 9 is a cross-sectional view whereas FIG. 10 is across-sectional perspective view. Here, FIG. 9 shows the configurationof only a part of the disk rotating motor.

Referring to FIGS. 9 and 10, the present embodiment is different fromthe second embodiment in the position of a suction magnet 44. Suctionmagnet 44 is fitted to the outer peripheral surface of a folded portion23 e, on a stator core 21. Suction magnet 44 is fixed to the outerperipheral surface of folded portion 23 e, in such a manner as to bebrought into contact with stator core 21.

Incidentally, the configuration of a motor 100 except theabove-described matter is identical to that of the motor in the secondembodiment, and therefore, its description is not repeated here.

In the present embodiment, the position of suction magnet 44 can berestricted by stator core 21. As a consequence, suction magnet 44 cansuck rotor 10 by uniform suction force.

[Fourth Embodiment]

FIG. 11 is a cross-sectional view schematically showing theconfiguration of a disk rotating motor in a fourth embodiment accordingto the present invention.

Referring to FIG. 11, the present embodiment is different from thesecond embodiment in that a bracket 23 further includes a separatingportion 23 g, on the boundary between a cylindrical portion 23 d, and afolded portion 23 e. Separating portion 23 g, extends in a radialdirection from the upper end of cylindrical portion 23 d in FIG. 11toward the upper end of folded portion 23 e, in FIG. 11. Separatingportion 23 g, is adapted to separate cylindrical portion 23 d, andfolded portion 23 e, from each other, thereby providing a clearance dtherebetween.

Incidentally, the configuration of a motor 100 except theabove-described matter is identical to that of the motor in the secondembodiment, and therefore, its description is not repeated here.

In the present embodiment, the radial length of separating portion 23 g,can adjust the radial position of folded portion 23 e. As a consequence,stator cores 21 having various sizes can be disposed in bracket 23.

[Others]

The disk rotating motor according to the present invention may beexemplified by an axially fixed motor, a planar opposite motor, and thelike in addition to the above-described axially rotational motor.

The above-described embodiments may be appropriately combined with eachother. In the case where bracket 23 includes separating portion 23 g, incombination of the configuration shown in FIG. 9 with the configurationshown in FIG. 11, suction magnet 44 may be fitted to the outerperipheral surface of folded portion 23 e, on stator core 21.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the scopeof the present invention being interpreted by the terms of the appendedclaims.

What is claimed is:
 1. A disk rotating motor comprising: a statorincluding a stator core and a bracket for fixing said stator core; arotor that can be rotated with respect to said stator and includes arotary shaft; and a bearing that rotatably supports said rotary shaft onthe outer diameter side of said rotary shaft; said bracket including acylindrical portion extending along said rotary shaft, and a foldedportion formed by folding the end of said cylindrical portion onto theouter diameter side such that at least a coaxial part of the foldedportion extends coaxially along an outer circumferential surface of thecylindrical portion, and said bearing being fixed to an innercircumferential surface of said cylindrical portion whereas said statorcore being at least in part fixed to an outer peripheral surface of thecoaxial part of said folded portion.
 2. The disk rotating motoraccording to claim 1, wherein said bracket further includes bottomformed by bending the end of said cylindrical portion onto an innerdiameter side, said bottom supporting one end of said rotary shaft. 3.The disk rotating motor according to claim 2, further comprising athrust plate having a contact surface that is brought into contact withone end of said rotary shaft, wherein said bottom includes a firstbottom in contact with said thrust plate at a surface opposite to saidcontact surface and a second bottom that is formed by bending said firstbottom and surrounds the outer periphery of said thrust plate.
 4. Thedisk rotating motor according to claim 1, further comprising a suctionmagnet that magnetically sucks said rotor.
 5. The disk rotating motoraccording to claim 4, wherein said suction magnet is fixed at the outerperipheral surface of said bearing in such a manner as to be broughtinto contact with the boundary between said cylindrical portion and saidfolded portion.
 6. The disk rotating motor according to claim 4, whereinsaid suction magnet is fixed at the outer peripheral surface of saidfolded portion in such a manner as to be brought into contact with saidstator core.
 7. The disk rotating motor according to claim 1, whereinsaid bracket further includes a separating portion that separates saidcylindrical portion and said folded portion from each other on theboundary between said cylindrical portion and said folded portion.
 8. Adisk drive device comprising: said disk rotating motor according toclaim 1; and a controller that controls the drive state of said diskrotating motor.